1. Field of the Invention
The invention relates to an unfolding bolt tightening spanner or wrench.
2. Discussion of the Background:
Difficult access to bolts, for example, occurs when assembling or disassembling the superimposed rings of a compressor drum, which are assembled by flanges located on the side of the inner wall of the rings and between circular walls occupying most of the drum cross-section and which only leave room for the passage of a tool in a central well or shaft having a diameter smaller than the width of the drum rings between the well and the axis of the bolts. The problem then consists of lowering the tool in a retracted position along the axis of the drum to the desired height, then moving it in a direction perpendicular to the drum axis in the gap between two rings in order to reach the bolts of a flange, which is not possible with conventional tools.
The technical field has numerous more complex tools having transmission means and trains of various types between the portion from where the tool movement is controlled and the bolt tightening location. These tools are generally unsuitable either as a result of their lack of rigidity making it impossible to guide them with a sufficient accuracy in bent cavities (this being the case with spanners formed from sections joined by ball and socket joints), or due to their shape, which is only suitable for particular applications, or by their being not very practical use.